Objective: This proposal is for a CDA-2 mentored training program that will transition Samuel Edwards, MD, MPH into an independent VA health services researcher who has special expertise in the design, function and evaluation of care models for medically and socially complex Veterans. The overarching objective of the research plan is explore what features of VA Home Based Primary Care (HBPC) drive its success in reducing hospitalizations for ambulatory care sensitive conditions, and use these insights to develop an intervention to promote best practices in HBPC. Research Plan: Dr. Edwards will conduct three studies using mixed methods. The research approach will draw upon the literature on patient complexity, core features of primary care, and the chronic care model. The Specific Aims of the proposed research are to: 1) Characterize patterns of enrollment and care delivery within HBPC, and determine clinical and systems correlates of preventable hospitalizations, 2) Assess HBPC providers perceptions of appropriate patient selection and care delivery patterns, core functions of HBPC, and barriers and facilitators to HBPC performance, and 3) Develop and test a pilot intervention to promote best practices in HBPC. Methods: Aims 1 and 2 will consist of an explanatory sequential mixed methods study exploring HBPC patient selection, care delivery patterns, core functions of HBPC. Aim 1, is a quantitative study consisting of four secondary analyses of national VHA data to (1) determine predictors of enrollment in HBPC, (2) define clinical subgroups of HBPC patients, (3) describe care delivery patterns within HBPC, and (4) determine association of patient subgroups and care delivery patterns with ambulatory care sensitive hospitalizations. Aim 2 is a two phase qualitative study. In the first phase, we will perform an in depth study of our local HBPC program using interviews, focus groups and structured observation. Second, we will perform interviews with program directors at other HBPC programs to gain a broader understanding of differences between sites. In both phases we will explore perceptions of the patient selection process, appropriate care delivery patterns, and the importance of core HBPC functions focusing on 5 proposed domains: 1) strong provider-patient relationships, 2) medication management 3) addressing social determinants of health, 4) integration of palliative care, and 5) coordination of care. We also plan to explore provider perspectives on barriers and facilitators on HBPC performance. Finally, Aim 3 will be the development of a pilot intervention to promote best practices in HBPC learned from Aims 1 and 2, which will be tested locally in a trial. We will perform a formative evaluation concurrently focused on acceptability and feasibility, with a preliminary look at efficacy. The expected outcome will be preliminary data to support a multicenter trial of a refined intervention to be tested at multiple HBPC sites. Career Plan: Dr. Edwards is a physician-investigator with training in health services research methods and expertise in primary care redesign, team based care, and HBPC. This proposal will deepen his theoretical understanding, content expertise, and research skills. Specific areas for training are: 1) Qualitative and advanced quantitative skills that can be applied to mixed methods approaches in health services research; 2) Content expertise in patient complexity and home based primary care; and 3) Implementation science and intervention development. The training plan will consist of coursework, seminars, and readings guided by the mentorship team. Ultimately, these efforts will assist in Dr. Edwards reaching his goal of becoming a national leader in conducting research and testing care models directed at medically and socially complex Veterans.